#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a, b, c, d, x, y;
	scanf("%d %d %d %d", &a, &b, &c, &d);
	x = a > b ? a : b;
	y = c > d ? c : d;
	printf("%d", x > y ? x : y);
		

	return 0;
}